Electrical controlling device



Dec. 3, 1929.

J. w. GOODERHAM 1,738,293 ELECTRICAL CONTROLLING DEVICE Filed Janl'7,1928 2 Sheets-Sheet l 6 ll 9 5 T 14 1 Jfii 15 Z) \:-5

da/m/ 1 ioaam/mM 15) W 1 ATTOEA/[V 1929. J. w. GOODERHAM ELECTRICALCONTROLLING DEVICE Filed Jan. 17, 1928 2 Sheets-Sheet 2 //VVE/V do/wv M4GOODERHAM WW Patented Dec. 3, 1929 j UNITED STATES PATENT OFFICE JOHN W.GOODERHAM, OF LARGHMON'I, NEW YORK, ASSIGNOR TO BELL TELEPHONELABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A. CORPORATION OF NEWYORK ELECTRICAL CONTROLLING DEVICE Application filed January 17, 1928.Serial No. 247,309.

Devices have been proposed heretofore for periodically reversing thecurrent in the calling subscribers line during conversation to operate ameter located at the substation. It has also been proposed to usevariable resistance elements, such as tungsten lamps, for effecting agradual change in the current on re versal to prevent disturbances inthe line. In these systems the resistance elements are in circuitcontinuously, whereas they are effective only for a comparatively smallportion of the time.

According to the present invention an advantage over these prior devicesis secured by providing a mechanism which automatically connects a setof tungsten lamps to the reversing circuit just before and disconnectsthe lamps therefrom just after reversal talres place. The resistance ofthe lamps, being least when the filaments are coldand graduallyincreasing as the filaments heat, serves to prevent sudden changes ofcurrent in the subscribers line. y

A feature of the invention is a reversing mechanism in which certain ofthe lamps have higher normal resistances than others and are connectedto the line in such manner that this difference of resistance causes thecurrent in the subscribers line to change gradually from a high value inone direction to zero and then to build up in the opposite direction.

In the drawing Fig. 1 illustrates diagrammatically a telephone systemembodying the invention. Fig. 2 shows a modification of the invention. ja j j y Referring to Fig. 1, the subscribers" lines appear at anoperators position. Two of these lines, the line A, represented as acalling line, and the line B,represented as the called line, are shownterminating in jacks 3 and 5 respectively at the operators position. Thelines A and B are equipped respectively with service meters 1 and '2located at the substations. These meters are arranged to operate atsuccessive intervals during the conversation in response to repeatedreversals of current in the line.

The central oflice circuits are so arranged that during the time theconnection is established the direction of current from the source,which supplies the calling line for talking purposes, is periodicallyreversed. These reversals are effected by means of a re lay 12 whichenergizes and releases alternately at 15-second intervals, for instance.Since conversation is taking place during the time the reversals arecaused, it is necessary to make some provision against sudden changes ofcurrent in the subscribers line and the consequent annoying sounds inthetelephone receiver. To thisend a group of tungsten filament lamps 19,20, 21 and 22 forming a WVheatstone bridge, are arranged to be connected to the line just before reversal takes place and to bedisconnected therefrom slightly after the reversal. The property of atungsten lamp, whereby its resistance is substantially less when thefilament is cold than when heated, is employed to effect a uniformchange in the current strength at the time the circuit is broken by thereversing relay 12.

The reversing equipment is associated with the operators cord circuit Cin such a manner that current from the source is supplied through theleft windings of the repeating coil 7 to the calling subscribers line.Since no reversal occurs in the called subscribers line his meter is notoperated. i

A detailed description of the operation will now be given of the systemshown in Fig. 1. Assume that the subscriber of line A i wishes toconverse with the subscriber of line B. The calling party initiatesthecall in the usual manner and the operator responds by inserting theplug l of the cord circuit C in the jack 3. "When the plug is insertedin the jack a circuit is completed from battery through the lamp 15,resistance 10, sleeve of the plug and jack to ground. At the same timeanother circuit is closed from battery through the right back contact ofrelay 12, lower left winding of repeating coil 7, supervisory'relay 8,ring of the plug and jack and thence overthe subscribers line andreturn- I thereupon completes ing'the plug '6 in the 16 lights inthiscircuit.

. about reversals of pletesfa circuit from batter tact, resistances :11and 10, and thence to the "completed from winding of coil ficu'it andcloses I its contact, left 'vvin'din'g "ance'23, conductor 25 to I sureof this latter circuit shunts the lamp l6 and '18 effective.

ing over the tip side of the connection through the upper left windingof the coil 7 to ground at the left back contact of relay 12.

he relay 8 operates in this circuit'an'd comthrough its con groundedsleeve conductor. This latter circuit shunts the lamp 15 causing thesame to remain extinguished. I

The operator communicates with the call-- ing subscriber in theWell-known manner and the connection by insertjack 5 of the called lineplug 6 completes a cirhe insertion'of through the lamp 16, re-

'cuit, from battery 's1s'tance'23,conductor 25, through the sleeve oftheplug Gandjack 5 to ground. Lamp Ringing current is supplied to thecalled subscribers line in the usual manner. r When the called partyanswers, a'circuit is battery to the lower right 7, winding ofsupervisory relay9, thence over the ring side of the called line andreturning over the tip side through I theupper right winding of coil7'to ground.

in this cira circuit from battery through of relay 13, resistground. The010- The' supervisory relay 9 operates and extinguishes it, andalso'causes the operation offrelay 13. The relay 13 locks in a circuitfrom battery through its right winding and contact to the'groundedconductor 25.

e relay13 'renders'the interrupters 17 The interrupter 17 causes releaseof relay 12 to bring current/in the calling line.

the operation and The interrupter 18 operates andreleases the relay 1 1to connect the lamps to and disconnect them from the subscriberslineduring the period reversal is taking place. The

ihterrupters17 and 18 are so related't-hat the relay '14 operatesa shortinterval'before relay I, 12ioperates-a'nd releases a short intervalafter it operates. Relay 1 1 also operates a short I interval beforerelay 12 releases and releases shortly after the release of relay 12.]In this I manner the lamps 19 to 22inclusive arefconne'ct e din-circuit'only, for the brief interval that the current is scribersline.

\ As solomfol'lowing being'reversed inth'e'subthe'oper'ation of relay'13, as the interrupter 18' closes jits contact,

relay 14 operates. Relay Hat-its right "contacts connects lamps 19 and20to conductor '26 and at its left' I contacts connects lamps 21 and 22 toconductor 27. Since the lamp 19'has battery connected toboth of itstermitors 26 and 27 is reduced to zero.

nals its filament remains cold and at its lowest resistance. A circuitfor lamp 20 is closed, however, from battery to the right back contactof relay 12, conductor 26, right contacts of relay 14, through thefilament of the lamp to ground. This lamp immediately heats itsfilament, increasing its resistanceto the maximum value. The same istrue of lamps 21 and 22, namely, the lamp-22 remains shunted while thelamp 21 lights and heats its filament. An instant later the interrupter17 closes its contact and relay 12 operates. As relay 12 breaks its backcontacts, full hattery and ground potential is removed from conductors26 and 27 respectively. The subscribefis line instead of being openedabruptly, however, is connected through cold lamps 19 and 22 to batteryand ground, the direction of current flow remaining the "same.

Since current commences to fiowthrough'the theirresistancesare'substantially equal. The

s'ameis true in respect to the lamps'21 and 22.

Thus, while the armatures of relay 12 are moving from their 'backto'theirfront contacts the current flowing in the subscriber's line'isuniformly reduced "substantially to 'z'ero. It will be noted thatsinc'e'thc lamps 19 and 20 reach a point of sub'stantially'equalresistance and lamps 21 and 22 actin th'esame manner, the potentialdropac'ross' th'e' conduc- 'When the circuit has reached this condition12 makes its front contacts an'dcurrent builds up in the subscribersline in the opposite direction, thus completing the reversal. Thesubscribers meter being of the polarized type responds to this reversaland records'one count on the metering train. Shortly after relay 12makes its front contacts, the interrupter 18 opens its contacts andrelay 14 releases, disconnecting the lamps and permitting them to cooltheir filaments.

Fifteen seconds later the interrupter 17 opens its segment permittingthe relay 12 to release. Just prior to the release of relay '12 theinterrupter 18' completesthe circuit for relay l i'toconnect' the lampsto the conductors 26 and 27. This time th'e l'amps 20 and "21 areshunted a'ndthe lamps 19 and 22am illuminated. \Vhen the relay breaksitsfront contacts the lamps 20 and 21 rapidly heat their filaments causinga uniform changehf current in the subscribers linein the manner aie matem shown in Fig. 2 of the drawing.

tinues as long as the connection is established.

The relay 14, when operated, maintains a shunt around the lamp toprevent it from flashing should relay 8 momentarily release during thereversing operation.

At the end of conversation the subscribers replace their receivers onthe switchhooks. The calling subscriber causes the release of relay 3removing the shunt and permitting the lamp 15 to illuminate. The calledsubscriber releases relay 9 which opens the shunt circuit for lamp 16and this lampbecomes lighted. The operator in response to these signalstakes down the connection and relay 13 releases.

A description will now be given of the sys- In this figure thesubscribers lines A and B appear in jacks and 33 respectively at theoperators position and are equipped with meters similar to lines A and Bpreviously described.

In this figure, however, the current reversing circuit is somewhatdifferent. The lamps 49 to 52 inclusive are included in circuit with thesubscribers line by means of relays 47 and 48. Relay 47 is controlled byinterrupter 46 and relay 48 by interrupter 45.

The reversing relay is controlled by the interrupter 44. Theinterrupters are so arranged that the relay 47 operates just prior tothe operation of relay 40 and releases just after relay 40 has operated.The interrupters are further arranged such that the relay 48 i isoperatedjust prior to the release of relay 40 and released imn'iediatelyafter the release of relay 40.

The lamps 49 to 52 form a VVheatstone bridge and are selected withdifferent re sistances. In other words, the lamps 49 and 51 when coldhave a higher resistance than the lamps and 52 when cold. When the lamps50 and 52 are heated, however, their resistance rises to a value higherthan the cold resistance of lamps 49 and 51. Furthermore, the resistanceof lamps 49 and 51 when heated is greater than the resistance of lamps50 and 52 when heated. As will be explained hereinafter, thisarrangement of resistances enables a shifting of the bridge balance anda gradual reduction in the current flowing in the subscribers line fromits maximum value in one direction to zero and the gradual increase ofcurrent in the opposite direction during the reversal operation.

When the subscriber of line A initiates a call the operator inserts theplug 31 of the cord C in the jack 30. A circuit is thereby closed forthe supervisory lamp 38. Moreover a circuit is completed from batterythrough the right back contact of relay 40, coil 53, lower left windingof repeating coil 34, relay 35, through the ring of the plug and jack,over the subscribers loop, and returning on the tip side to the upperleft winding of coil 34, coil 54 to ground at the left contact of relay40. Relay 35 operates and closes a circuit through resistances 39 and 37to shunt the lamp 38.

Obtaining the number wanted by the calling subscriber, the operatorinserts the plug 32 in jack 33 which results in the closure of thecircuit for lamp 42. After ringing current is applied the calledsubscriber answers and relay 36 operates. Relay 36 closes a circuitthrough the left winding of relay 43 and shunts the lamp 42. Relay 43looks through the sleeve of the plug and jack.

As soon, following the operation of relay 43, as the interrupter 46closes, a circuit is completed from ground through the contacts of theinterrupter, contact of relay 43, wine ing of relay 47 to battery. Relay47 operates and connects the lamps in circuit. The lamp 49 is includedin a circuit which leads from ground through the left back contact ofrelay 40, filament of said lamp to ground through the left contact ofrelay 47. Since both terminals of the lamp are grounded the filamentremains cold and, therefore, at its lowest resistance. Similarly thelamp 51 is connected from battery to battery and its filament remainscold. Lamp 50 is included in a circuit from ground, through the leftback contact of relay 40, filament of said lamp, to battery through theright contact of relay 47. Similarly lamp 52 is included in a circuitfrom battery, through the right back contact of relay 40, filamentoflamp 52, to ground at the left contact of relay 47. Lamps 50 and 52,therefore, light their filaments and in crease their resistance to itsmaximum value which, as above explained, is greater than the coldresistance of lamps 49 and 51.

An instant later the interrupter 44 closes its contact and operates therelay 40. The in stant relay 4O breaks its back contacts the directbattery and ground connections are removed from the subscribefis line. Acircuit may now be traced from battery through the middle right contactof relay 47, lamp 51, conductor 56, and thus over the subscribefls lineand returning to conductor 55 through the lamp 49 and ground at the leftouter contact of relay 47. Current is supplied to the subscribers linein this circuit and continues to flow in the same direction. The lamps49 and 51, however, commence to heat their filaments, correspondinglyincreasing their resistance and gradually reducing the value of thecurrent flowing in the subscribers line. Furthermore. the directcircuits of lamps 50 and 52 are opened and these lanips are now includedin series with the lamps 49 and 51 respectively. Accordingly lamps 50and 52 receive less current and accordingly reduce their resistances.Thus the resistance of lamps 49 and 51 gradually increases and theresistance of lamps 50 and 52 gradually decreases. This being the casethe resistance of lamp 49 becomes equal to the resistance of lamp 50 andthe resistance of lainp 51 becomes-equal'to that of -2 at a time beforethe lamps 49 and 51 are fully heated. VVl1en the lamps have reached apoint ote aai resistances the potential-across conductors 55 and 56 hasreached zero and no current flows over the subscribers line. Since,however, the lamps 49 and 51 continue to increase tileiTTG- sistance adifference of potential is created between conductors 55 and 56, thedi-tterence being such that current now 'floivs'over the subscribersline in the opposite direction. This current will continue to increasegradually until the lamps 49an'd 51 reach their highest resista'nce'andlamps 50 and 52 reach their lowest'fresistance. :bhortly after this therelay "40 makes its front co'nt'actand'full battery potential in thereverse direction is applied across conductors'55 and 56. Shortly afterrelay 40 closes itsfrolnficonta'ctS-the interrupter 46 opens and relay4? relea At" the end of seconds for instance, the interrupter 44 opensits contact and releases relay 40. Just before relay releases,interrupte'r45 closes and operates the relay 1 8. Relay'48 includes thelamp 49 in a circuit from battery to battery, andthe lamp Si in'acirc'uit from ground to ground 'so that these lamps remain cold asbefore. Lamps 50 and 52 are included-1n energizing circu1ts,"however,and lighttheir filaments. lVhen-relay '40 breaks its front contacts,lamps 49 and 51 are included in circuit With-theline'and cause thegradual reduction of the current therein to zero and it is graduallyincreased in the opposite direction as above explained. An instant laterrelay '40 closes its back contacts and full potential is "applied "tothe subscribers line in the original direction. Shortly thereafter therelay 48 releases and disconmeets the lamps; v

In this manner -the current in the subscribers lineis reversedperiodically for operating the substation meter andthe intensity of thecurrent is so controlled as, not to cause any disagreeable clicks in thesubscribers connection Witha manual system it understood that it'may beapplied to At the end of conversationthe connection is released in theWell-known manner.

l/Vhilethe invention has been illustrated in is to be systems employingautomatic switches. It is also to ,be understood that numerous changesand alterationsmay be made and'that ber 22,1914.

carrying element the resistance of varies in response to the flow ofcurrent What is claimed is:

-1. In combination, a telephone line, a meter therefor, a source forsupplying current to said line, means for connecting said source incircuit Withthe line, means for altering the connection of the supplysource to said line to cause the operation of said meter, a vari ableresistance element for preventing sudden changes of current in saidline, and means for putting said element into use prior to thealteration of said connection and for taking it out of use subsequent tosaid alteration.

2. In combination, a telephone line and a meter therefor, a sourceforsupplyingpcurrent to said line and for operating said meter, meansforconnecting said source in circuit with the line, means for repeatedlyinterrupting the connection of the supply source to said line, avariable resistance element for preventing abrupt changes of current insaid line, and means for closing a connection for said element to renderit effective prior to each interruption of said connection and fordisconnecting said elementsubsequent to each interruption.

3. In a telephone system, a subscribers line and a meter therefor, abattery for supplying current to said line, means for reversing the flowof current in said line to operate the meter, a variable resistanceelement for preventing sudden changes of current in said line, and meansfor placing said element in circuit with the line prior to and forremoving it from circuit subsequent to saidreversal.

, 4. In a telephone system, a subscribers line and a meter therefor, asource of current for supplying said line, means for connecting saidsource in circuit with the line, means for periodically reversing thedirection of current flow in the line to repeatedly operate said meter,a variable resistance element for preventing sudden changes of currentdue to said reversals, and means for automatically connecting saidelement in circuit before each reversal and disconnecting it therefromafter each reversal.

5.'In combination, a telephone line and a meter therefor, a source forsupplying current to said line and for operating said meter, means-forconnecting said source in circuit with the line, means for interruptingthe connection of the source to said line, a current which therein, saidelement serving to prevent sudden changes in current in the line,'andmeans for connecting said element in circuit before and disconnecting itfrom circuit after the -interruptionof said connection.

6. In combination, a subscribers line and a meter therefor, a source forsupplying current to said line, means for reversing the direction ofcurrent flow in the line to cause the operation. of said meter, acurrent carrying element the resistance of which increases as ing thedirection of current in the line to operate said meter, a closed chamberhaving a tungsten filament therein, the resistance of which increases asits temperature rises due to current flow therethrough, and means forincluding said filament in circuit prior to re versal and removing ittherefrom subsequent to reversal.

8. In combination, a telephone line and a meter therefor, a source forsupplying talking current to said line, means for repeatedly reversingthe direction of current flow in the line to operate said meter,aplurality of lamps normally disconnected from the line, and means forconnecting said lamps in circuit with the line during each successivereversal to prevent abrupt changes of current in the line.

9. In a telephone system, a subscribers line, a current operated devicetherefor, a source for supplying current to said line, means forchanging the flow of current from said source to operate said device, avariable resistance device cooperating with said means for causing thecurrent to gradually decrease in one direction and to gradually increasein the opposite direction, and means for con necting said last device incircuit prior to said change of current and for disconnecting itfromcircuit subsequent thereto.

10. In a telephone system, a subscribers line, a current operated devicetherefor, a source for supplying current to the line, means for changingthe flow ofcurrent from said source to operate said device, a currentcarrying device the resistance of which varies in response to the flow 0current therein, said last mentioned device cooperating with said meansfor causing the current to gradually decrease in one direction and togradually increase in the opposite direction, and means for connectingsaid last mentioned device in circuit prior to each change of currentand for disconnecting it from circuit subsequent to each change.

11. In combination, a subscribers line, a meter for said line, a sourceof current for supplying the line, means for changing the di rection ofthe current to operate said meter, lamps having variable resistances andcooperating with said current changing means in such a manner as tocause a gradual de crease of the current in one direction and a gradualincrease in the opposite direction in the subscribers line, and meansfor connecting said lamps in circuit prior to the current change and fordisconnecting them subse quent to such change.

12. In combination, a line, a current controlled device for said line, acurrent source for supplying the line, two current carrying elements theresistances of which vary in response to the flow of currenttherein,said elements having difi erent normal resistances, means for connectingsaid elements to the line in such manner that the resistance ofoneincreases while that of the other decreases to effect a gradualchange of current flow in said line, and means responsive to saidcurrent change for operating said device.

13. In combination, a line, a meter for said line, a source of currentsupplying the line, tWo current carrying elements the resistances ofwhich change in response to the flow of current therein, said elementshaving different normal resistances, means for connecting said elementsto the line in such manner that the difi'erence between theirresistances varies to effect a gradual change of current flow in saidline, and means responsive to the change of current in the line foroperating said meter.

14:. In a telephone system, a subscribers line and a meter therefor, asource of current for applying the line, aplurality of current carryingelements the resistances of which change in response to the flow ofcurrent therein, means for connecting said elements to the line in suchmanner that the resistances vary to cause the current to changeuniformly from its value in one direction to a given value in theopposite direction, and means responsive to such change of current foroperating said meter.

15. In combination, a line, a source of current for supplying the line,two lamps the resistances of which vary in response to the flow ofcurrent therein, said lamps having different normal resistances, andmeans for periodically connecting said lamps to the line in such mannerthat the resistance of one increases while the resistance of the otherdecreases to effect a gradual change of current flow in the line.

16. In combination, a line, a current controlled device for said line,means for supplying current to the line, a Wheatstone bridge havingelements the resistances of which vary in response to current flowtherein, the normal resistances of said elements being such that thebridge is unbalanced, means for connecting said bridge to the line insuch manner that it gradually assumes a condition of balance to cause auniform change of current in said line, and means responsive to the flowof current in said line for operating said device.

17 In combination, a circuit and a current controlled device therefor, asource of current for supplying the circuit, a Wheatstone bridge havinglamps for its resistance elements, the resistances of said lamps varygin r p cts tn the flow o c rrent th re m i so the values of saidresistanses being such that flr bi' 'idg is normal-1 unbalanced, meansfor qijnnsct'ing th bridge to said circuit in such niannr that itgradually assumes first a cond'it'i-bn' of balance and then a; conditionofunbalance to change the flow of current in said c lt', and meansresponsive to 'the change current flow f0;- o'per'at 'ng said device.

In wit;nes's whereof,' I here'unto' subscribe my l sting this 13thd a ofJanuary, 1928.

